feat: cosmetic tweaks for Neovim

[wincent]

This is a draft for now because it would require bigger changes to directory layout in order to fully complete it. If you want me to make those changes, let me know and I can update.

Before this PR

After this PR

With a syntax file

---

That last screenshot shows what the non-breaking spaces are all about: they provide us with something we can conveniently syntax-highlight to make the headers stand out:

if vim.fn.exists('main_syntax') == 0 then
  if vim.fn.exists('b:current_syntax') == 1 then
    return
  end
  vim.g.main_syntax = 'shellbot'
elseif vim.fn.exists('b:current_syntax') == 1 and vim.b.current_syntax == 'shellbot' then
  return
end

vim.cmd('runtime! syntax/markdown.vim')

local cpo = vim.o.cpo

vim.cmd([[
  set cpo&vim
  syntax match ChatBotHeader /^ 🤓 .*/ containedin=ALL
  syntax match ChatBotHeader /^ 🤖 .*/ containedin=ALL
  highlight def link ChatBotHeader TermCursor
]])

vim.b.current_syntax = 'shellbot'
if vim.g.main_syntax == 'shellbot' then
  vim.api.nvim_del_var('main_syntax')
end
vim.o.cpo = cpo

So, why can't I include the syntax file in this PR? Because syntax files have to live under a syntax directory, but the repo doesn't have the right layout right now; ie. the current layout is:

<root>
├── Cargo.lock
├── Cargo.toml
├── LICENSE
├── README.md
├── chatbot.lua
├── shellbot
│   └── health.lua
├── shellbot.sh
└── src
    ├── anthropic.rs
    ├── api.rs
    ├── main.rs
    ├── openai.rs
    └── sse.rs

but the final layout would need to be something like:

<root>
├── Cargo.lock
├── Cargo.toml
├── LICENSE
├── README.md
└── lua
|   ├── chatbot.lua
|   └── shellbot
|       └── health.lua
└── syntax
|   └── shellbot.lua
├── shellbot.sh
└── src
    ├── anthropic.rs
    ├── api.rs
    ├── main.rs
    ├── openai.rs
    └── sse.rs

ie.

• move Neovim lua files into lua subdirectory; this is where Neovim expects to find Lua files such that they can be imported with require('shellbot').
• create syntax/shellbot.lua; standard location for syntax files, automatically loaded when shellbot 'filetype' is activated.

[wincent]

Draft for now for reasons indicated. Let me know what you think, @wolffiex.

[wolffiex]

This is awesome! Thanks for the contribution!

[wincent]

Superseded by:

• Bundle changes and restructure #12